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white longitudinal dashes are more numerous and towards the 

 dorsal area quite crowded. In one specimen the whole of 

 one valve is green and others are blotched with green. Most 

 of those from that locality exhibit a large amount of pink; 

 in these the beak is pink, this colour spreading over fully one- 

 third of each valve. These specimens are extremely pretty, 

 striped with white, banded with brown, extensively washed 

 with pink and blotched with green. The pink shade seems 

 near to what is described in Ridgway (plate as above) as 

 salmon -orange. 



Anterior Valve. — Slope steep, 9 raised radiating ribs, 

 which, with the two posterior margins, are composed of a series 

 of large, flattened, more or less circular pustules, smaller at the 

 apex, and increasing rapidly towards the margin. These 

 pustules give a crenate appearance to the margin of valve at 

 the suture. Inside, white tinged with greenish-blue, slits 8, 

 edges of teeth rounded and thickened, some show slight 

 notching. 



Posterior Valve. — Valve small, mucro- terminal, elevated, 

 sinus below, a thickening extending from the mucro forwards 

 to near the anterior margin. A bow-shaped continuation 

 of the tegmentum extends behind the diagonal rib, downwards. 

 The anterior margin on many specimens also shows thicken- 

 ing. Except for grooves following the growth-lines, un- 

 sculptured. Inside sinus wade, anterior margin of sutural 

 laminae parallel with margin of tegmentum and almost 

 straight, white tinged with greenish-blue, unslit, with a broad 

 sinuosity under the upturned tail. 



Median Valve. — Beaked, side slope rather flat, in some 

 slightly rounded; dorsal area raised towards the posterior 

 margin and rounded, defined by a pale wedge-shaped mark 

 which is closely subgranulose ; in places, these irregular 

 longish granules are defined, in others they are coated over 

 with a smooth outer coating. The lateral area is defined by 

 two raised ribs composed of coarse, flattened, elongated pro- 

 trubrances or pustules, set on a diagonal, well defined on the 

 posterior margin, but on the other rib ill-defined, although 

 distinctly raised. The space between these ribs is smooth, or 

 almost so, but not polished. The pleural area is in the 

 type specimen occupied by a series of coarse, broad, wavy 

 ribs separated by irregular wavy sulci. This method of 

 sculpture suggests "ripple marks" on a sandy sea beach. 

 Inside, white tinged with greenish-blue, 1 slit, which is deep 

 and well defined, pillared or produced upwards under the 

 eaves at each side of slit. The eaves are defined, but the 

 insertion plates are produced beyond the eaves. 



Girdle. — When cleaned by boiling the girdle is found, 

 under a magnification of 28 diameters, to be covered with a 



